<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>奥运五环</title>
    <style type="text/css">
        *{
            margin: 0;
            padding: 0;
        }
        .wrapper{
            width: 780px;
            height: 370px;
            border:1px solid black;
            position: absolute;
            left: 50%;
            top: 50%;
            margin-left: -390px;
            margin-top: -185px;
        }
        .circle{
            width: 200px;
            height: 200px;
            border-radius: 50%;
            position: absolute;
        }
        /*蓝黑红黄绿*/
        .blue{
            border:20px solid blue;
        }
        .blue2{
            border:20px solid transparent;
            border-right-color: blue;
            z-index: 2;
        }
        .black{
            border:20px solid black;
            left: 270px;
        }
        .black2{
            border:20px solid transparent;
            border-bottom-color: black;
            border-right-color: black;
            left: 270px;
            z-index: 2;
        }
        .red{
            border:20px solid red;
            left: 540px;
        }
        .red2{
            border:20px solid transparent;
            border-left-color: red;
            left: 540px;
            z-index: 2;
        }
        .yellow{
            border:20px solid yellow;
            left: 140px;
            top:130px;
        }
        .green{
            border:20px solid green;
            left: 410px;
            top:130px;
        }
        .green2{
            border:20px solid transparent;
            border-left-color: green;
            left: 410px;
            top:130px;
            z-index: 2;
        }
    </style>
    </head>
    <body>
        <div class="wrapper">
            <div class = "circle blue"></div>
            <div class = "circle blue2"></div>
            <div class = "circle black"></div>
            <div class = "circle black2"></div>
            <div class = "circle red"></div>
            <div class = "circle red2"></div>
            <div class = "circle yellow"></div>
            <div class = "circle green"></div>
            <div class = "circle green2"></div>
        </div>
    </body>
    </html>